You may have heard about special events, like walks or races, to raise money for breast cancer research. Or maybe you've seen people wear those little pink ribbons on their clothes.

Breast (say: brest) cancer is a common cancer among women. It occurs rarely in men and it doesn't affect kids. But kids might want to learn about it because they know someone who has it or because they want to learn how to check for it when they are older.

What Is Breast Cancer?

The human body is made of tiny building blocks called cells. Your body creates them, replacing those that die with new ones. Usually, the body creates healthy, normal cells that do just what they're supposed to do. This includes cells in the breasts, the two rounded areas on the front of the chest.

But if a cell changes into an abnormal, sometimes harmful form, it can divide quickly over and over again without dying, making many, many copies of itself. When this happens, a tumor, abnormal body cells grouped together in the form of a mass or lump, can start to form and grow.

Breast cancer is a kind of tumor that develops in the cells of a person's breast. You may think that only women can get breast cancer, but because all people have breast tissue, men can get breast cancer as well — but this is very rare.

Someone with breast cancer may have cancer cells in just one part of the breast, which might be felt as a lump. The cancer can spread throughout one or both breasts. Sometimes breast cancer spreads to other parts of the body, like the bones<, the liver, or elsewhere.

Why Do People Get Breast Cancer?

Any woman can get breast cancer, but these things can make some women more likely to get it:

Family history: A woman whose mother, sister, aunt, or daughter has had breast cancer is more likely to get it.

Age: As women get older, they are more at risk for breast cancer. Teens — as well as women in their twenties and thirties — are less likely to get breast cancer.

Diet and lifestyle choices: Women who smoke, eat high-fat diets, drink alcohol, and don't get enough exercise may be more at risk for developing breast cancer.

What Are the Signs of Breast Cancer?

A woman who has breast cancer may have no problems, or she may find a painless lump in her breast. If women examine their breasts monthly, they can help find lumps or other changes that a doctor should examine.

Most breast lumps are not cancer, but all lumps should be checked out by a doctor to be sure. Breast lumps that are not cancer may be scar tissue or cysts (fluid-filled lumps or sacs) or they can be due to normal breast changes associated with hormone changes or aging.

Girls who are beginning puberty might notice a lump underneath the nipple when their breasts start developing. Usually, this is a normal. You can ask a parent or your doctor about it to be sure.

What Will the Doctor Do?

Sometimes a doctor will discover a lump in a woman's breast during a routine examination or a patient might come to the doctor with questions about a lump she found.

In other cases, a mammogram (say: MAM-uh-gram) may find a lump in the breast that can't be felt. A mammogram is a special kind of X-ray of the breast that helps doctors see what's going on inside. Sometimes, other kinds of pictures, like an MRI, also can be taken.

When a lump is found, the doctor will want to test it. The best way to do this is usually with a biopsy. In a biopsy, a small amount of breast tissue is removed with a needle or during a small operation. Then, the tissue is examined under a microscope to look for cancer cells.

The biopsy may be benign (say: bih-NINE), which means the lump is not cancer. If the biopsy shows cancer cells, the lump is malignant (say: muh-LIG-nunt). If a breast lump does contains cancer cells, the woman, along with her doctor and family, will decide what to do next.

How Is Breast Cancer Treated?

Treatment for breast cancer usually depends on the type of cancer and whether the cancer has spread outside of the breast to other parts of the body.

Here are some common treatments:

lumpectomy (say: lum-PEK-tuh-mee), which removes the cancerous tumor from the breast. A woman usually has this surgery when the cancer is found early and when the lump is small and in only one part of the breast.

mastectomy (say: ma-STEK-tuh-mee), which removes the whole breast. This surgery is done when cancer cells have spread through the breast or into other parts of the body. It's a good way to remove all or most of the cancer, and can help prevent the cancer from spreading or coming back. Sometimes, a woman who has a mastectomy may choose to have an operation to reconstruct (rebuild) the breast, so her shape will be more like it was before.

radiation therapy and chemotherapy, which are often used after lumpectomy or mastectomy to make sure that all the cancer cells are destroyed and do not grow back. Radiation (say: ray-dee-AY-shun) therapy uses high-energy X-rays to kill the cancerous cells. Chemotherapy (say: kee-mo-THER-uh-pee), or chemo, is special medicine that travels throughout the entire body and kills cancer cells.

Living With Breast Cancer

Dealing with breast cancer can be very hard for a woman and her family. A woman who has breast cancer surgery or treatment may not feel well for a while. She may be depressed if she had her breast removed. If a woman needs chemotherapy, she may lose her hair and she may feel sick to her stomach. She also may worry that the cancer will return and she'll get sick again.

The good news is that many times, especially if a lump is caught early, women with breast cancer go on to live full, healthy lives after treatment. Some join support groups so they can talk to other women with breast cancer who are feeling the same emotions.

There are even groups that kids or other family members can join to talk about their feelings when someone they love has breast cancer. Find a trusted adult to talk with if you're worried about a loved one.

Breast Cancer Prevention

Doctors and scientists are working to find cures for breast cancer. They are researching new medicines that may even help prevent the disease. But in the meantime, it's important for women to catch the disease early.

Regular mammograms — together with monthly breast self-exams — are the best ways for women to protect themselves. You may want to ask the women you care about if they are taking these important steps to stay healthy.